The present invention relates to positive displacement pumps. In particular, the present invention relates to gasoline powered positive displacement pump systems.
In the commercial market, high pressure, gasoline engine powered pumps are well known. For example, professional industrial painters employ high pressure gas powered pumps, also known as pressure washers, to prepare surfaces prior to painting.
In the consumer market, gasoline-powered high pressure washers are known, but the cost is high, and therefore consumer acceptance has been limited. In an effort to improve consumer acceptance, high pressure pump systems for consumer use have been designed which are driven by means of an electric motor. The electrically driven high pressure pumps have achieved some degree of consumer acceptance because of the lower cost, but have disadvantages.
The use of an electrical chord is cumbersome. The electrical chord must also include a ground fault circuit interrupter and be long enough to meet the safety requirements set forth by the National Electrical Code. If an extension chord is needed, only a heavy duty extension chord may be used due to the high amperes required for the electric motor. Both the ground fault circuit and heavy duty chord increase the cost of the device. Moving the extension chords as well as the water hose when using an electrically driven pressure washer can be a nuisance. The unit may also have to be unplugged, relocated and reconnected when using the pump for a large project. For example, when using an electrically powered pressure washer for washing the siding on a house before painting, it is necessary to reconnect the unit to the power source several times.
Another disadvantage of electrically powered high pressure pumps is limited capacity. The electrical circuits in most homes typically have a 15 amp capacity. The maximum size motor that can run on a 15 amp circuit is 11/2 horsepower. A pressure washer equipped with a 11/2 hp, 15 amp single phase motor delivers approximately 2 gallons per minute at 1000 pounds per square inch gauge (hereinafter p.s.i.). Gasoline powered pumps are capable of delivering a higher volume of liquid at higher pressures.
In an effort to overcome the disadvantages of electrically powered high pressure pumps, pumps designed for mounting onto a gas-powered engine with a vertically oriented rotational shaft have been developed. A typical gas-powered engine is a 5 horsepower lawn mower engine having a vertically disposed drive shaft which rotates at 3400 revolutions per minute under load. This type of engine is preferred because of its wide availability and relatively low cost.
Because the drive shaft of the gasoline powered engine is vertically oriented, the known pumps developed for coupling to such a shaft have required enough vertical distance between the end of the shaft and the pump base that the resulting unit is very tall and top heavy.
The taller pressure washers have also had limited success in the consumer market. The height and top heaviness of the resulting devices are distinct disadvantages. The product is awkward in appearance, and is unstable on uneven surfaces due to its weight and top heaviness. In addition, the cost of such a device high enough to limit market appeal.
It would be desirable to provide a low cost, low profile high pressure pump driven by a gasoline engine, the engine having a vertically disposed rotational shaft.